Thursday, December 15, 2016

C++11 : Template Class for Random Generator

"Anyone who attempts to generate random numbers by deterministic means is, of course, living in a state of sin." - John Von Neumann

Despite of the fact that the quote above is still highly relevant, we mostly get the job done well enough using those pseudo-random generators for our Monte Carlo stuff. So, this time I wanted to present a wrapper for simulating (sinful) uniform random numbers, which are then mapped to a chosen probability distribution. The main goal was to construct a lightweight design, using C++11 uniform generators, probability distributions as well as some other extremely useful tools (function, lambda) for the task.

TEMPLATE DIET

Instead of implementing any class hierarchies, I tried to keep this design as lightweighted as possible by using template class having only two template data types to be defined by a client : Generator (uniform random generator) and Distribution (probability distribution for transforming uniformly distributed random numbers). In a nutshell, a client may use any random number engine available in C++11, for creating desired amount of uniform random numbers. Moreover, a client may use default probability distribution (Standard Normal) for transforming created uniform random numbers or additionally, use any desired probability distribution available in C++11. Available uniform random engines and probability distributions have been nicely covered in here.

ULTIMATE SIN

It should be a bit easier to sell something, if the final product is nicely presented. Random numbers processed by example program (presented later) for four different random generator implementations are presented in Excel screenshot below.

HEADER FILE

Random generator template class is presented below. Note, that this implementation does not require any auxiliary libraries, since all the required stuff is already in C++11. For usability reasons, I decided to keep all the actual method implementations in header file (RandomGenerator.h).

TESTER FILE

Example program (tester.cpp) for testing random generator functionality is presented below. The process of generating (pseudo) random numbers from a probability distribution is easy and straightforward with this template wrapper class.

The programs, which are presented in this blog, can be freely used, but without warranty or support of any kind. By using the programs presented in this blog, you accept to bear the entire risk, concerning quality or performance of any programs used. In no event, will I be liable to you for the damages, including any general, special, incidental or consequential damages arising out of the use or inability to use the programs presented in this blog. By using the programs presented in this blog, you are accepting the content of this disclaimer.